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<a name="Statement-and-operand-traversals"></a>
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<a name="Statement-and-operand-traversals-1"></a>
<h3 class="section">12.12 Statement and operand traversals</h3>
<a name="index-Statement-and-operand-traversals"></a>

<p>There are two functions available for walking statements and
sequences: <code>walk_gimple_stmt</code> and <code>walk_gimple_seq</code>,
accordingly, and a third function for walking the operands in a
statement: <code>walk_gimple_op</code>.
</p>
<dl>
<dt><a name="index-walk_005fgimple_005fstmt"></a>GIMPLE function: <em>tree</em> <strong>walk_gimple_stmt</strong> <em>(gimple_stmt_iterator *gsi,   walk_stmt_fn callback_stmt, walk_tree_fn callback_op, struct walk_stmt_info *wi)</em></dt>
<dd><p>This function is used to walk the current statement in <code>GSI</code>,
optionally using traversal state stored in <code>WI</code>.  If <code>WI</code> is <code>NULL</code>, no
state is kept during the traversal.
</p>
<p>The callback <code>CALLBACK_STMT</code> is called.  If <code>CALLBACK_STMT</code> returns
true, it means that the callback function has handled all the
operands of the statement and it is not necessary to walk its
operands.
</p>
<p>If <code>CALLBACK_STMT</code> is <code>NULL</code> or it returns false, <code>CALLBACK_OP</code> is
called on each operand of the statement via <code>walk_gimple_op</code>.  If
<code>walk_gimple_op</code> returns non-<code>NULL</code> for any operand, the remaining
operands are not scanned.
</p>
<p>The return value is that returned by the last call to
<code>walk_gimple_op</code>, or <code>NULL_TREE</code> if no <code>CALLBACK_OP</code> is specified.
</p></dd></dl>


<dl>
<dt><a name="index-walk_005fgimple_005fop"></a>GIMPLE function: <em>tree</em> <strong>walk_gimple_op</strong> <em>(gimple stmt,   walk_tree_fn callback_op, struct walk_stmt_info *wi)</em></dt>
<dd><p>Use this function to walk the operands of statement <code>STMT</code>.  Every
operand is walked via <code>walk_tree</code> with optional state information
in <code>WI</code>.
</p>
<p><code>CALLBACK_OP</code> is called on each operand of <code>STMT</code> via <code>walk_tree</code>.
Additional parameters to <code>walk_tree</code> must be stored in <code>WI</code>.  For
each operand <code>OP</code>, <code>walk_tree</code> is called as:
</p>
<div class="smallexample">
<pre class="smallexample">walk_tree (&amp;<code>OP</code>, <code>CALLBACK_OP</code>, <code>WI</code>, <code>PSET</code>)
</pre></div>

<p>If <code>CALLBACK_OP</code> returns non-<code>NULL</code> for an operand, the remaining
operands are not scanned.  The return value is that returned by
the last call to <code>walk_tree</code>, or <code>NULL_TREE</code> if no <code>CALLBACK_OP</code> is
specified.
</p></dd></dl>


<dl>
<dt><a name="index-walk_005fgimple_005fseq"></a>GIMPLE function: <em>tree</em> <strong>walk_gimple_seq</strong> <em>(gimple_seq seq,   walk_stmt_fn callback_stmt, walk_tree_fn callback_op, struct walk_stmt_info *wi)</em></dt>
<dd><p>This function walks all the statements in the sequence <code>SEQ</code>
calling <code>walk_gimple_stmt</code> on each one.  <code>WI</code> is as in
<code>walk_gimple_stmt</code>.  If <code>walk_gimple_stmt</code> returns non-<code>NULL</code>, the walk
is stopped and the value returned.  Otherwise, all the statements
are walked and <code>NULL_TREE</code> returned.
</p></dd></dl>


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